Stable combination of cation- and anion-exchange resins



Patented Feb. 26, 1952 STABLE CONIBINATION OF CATION- AND ANION-EXCHANGE RESINS Grace Rose Stroll, Schenectady, N. Y., assignmto American Cyanamid Company, New York, N. Y., a corporation of Maine No Drawing. Application June 2, 1947, Serial No. 751,975

3 Claims. (01. 260-43) This invention relates to ion exchange materials and more particularly, to stable combinations of cation and anion exchange materials.

Ion exchange as a method by which ionizable solids may be removed from liquid media is known. Among the first developments in the field was the use of a single bed of a cation ac-- tive zeolite to soften water by replacing the metallic ions lending hardness thereto with sodium ions. It was later found expedient to use two beds of ion active material, one cation active and one anion active, in series and thus remove both cations and anions from liquid media. A most eiiective and efficient demineralization process has as one of its important features the use of a plurality of pairs of cation and anion exchangers.

The use'of a single bed of mixed cation and anion exchange materials in place of separate alternate beds thereof has also been described. Many advantages may be attained by the use of mixed cation and anion exchange materials. In the first place, such a mixture often gives more efiicient and more complete demineralization. Secondly, it permits the use of conventional types of equipment for liquid demineralization since it does not require any special equipment. As a result, mixed resins are useful in commercial installations either in the form of beds or as filter coatings and either in batch processes or in continuous processes.

Development in the field of liquid treatment by ion exchange processes has proceeded along another line simultaneously with that of the increased use of mixed ion exchange materials. Since purification of Water or, in general, removal of ionizable solids from liquid media by means of av multi-bed system involves the use of heavy equipment including metallic, porcelain, or wooden tanks of considerable size, and because of the heavy demand for a highly purified water of a quality comparable to distilled water in many places where stills are not available or where it would be difficult to transport the stills and equipment normally used in purifying water by means of ion exchange materials, a lightweight portable water purification unit has' seemed desirable, particularly for use in connection with military operations. As a result, disposable, portable cartridges containing alternate I beds of anion and cation exchange materials have been developed. The next step in the development was the packing of mixed ion exchange materials instead of alternate beds of such materials in disposable cartridges.

One outstanding disadvantage in the use of mixed resins whether they be part of a commercial installation or in a portable, disposable cartridge of one sort or another lies in the excessive waste of material originally considered necessarily inherent in processes using mixtures. The resins had to be discarded after they once became exhausted, and in view of the relatively high cost of ion exchange resins this procedure was not practical. This disadvantage has been overcome by the development of various processes for separating one resin from another in admixture.

Another and more critical disadvantage in the use of mixed resins is the instability of most mixtures of cation and anion exchange materials. Apparently upon combining the two types of materials a sort of neutralization of the effect of one by the other occurs since the capacity for the removal of ions from liquid media drops considerably in most cases after only a short time of contact.

It is an object of the present invention to provide a combination of anion and cation exchange materials which is stable over a period of time.

Another object of the present invention is to provide a stable combination of anion and cation exchange materials which has a shelf life of at least 24 weeks.

The above and other objects are attained by providing for liquid purification by ion exchange a combination of an anion active resin which is the reaction product of an alpha-chloro-beta,

gamma-epoxy compound and at least one alkylene polyamine in the ratio of at least two mols of epoxy compound per mole of polyamine with a cation active resin which is a phenolbisulfitealdehyde reaction product.

The invention will be described in greater detail in conjunction with the following specific examples which are merely illustrative and not intended to be restrictive of the scope of the invention.

Example 1 tivated and rinsed granular cation active resin Duolite C-3 sold by the Chemical Process Company, and an activated and rinsed anion resin A" prepared as described in detail below, said mixtures containing the cation; and-anion; resins in a 1:1 proportion by volume. Iniorp der to determine the initial capacity of the particular mixture a single cartridge. is exhausted by water containing 131 p. p. m. (parts permil lion) of sodium, 129 p. p. m. of chloride, a cal-. cium hardness of 130 p. p. m. and a bicarbonate alkalinity of 126 p. p. m., all quantities figured as' calcium carbonate. The resin mixture is found'to have aninitial capacity of 25 kilograinsas calcium carbonate per cubic foot'of cationresin asdetermined from the following data:

Properties of Efiiuent Specific Liters: resistance through mat g g' FMA 1 as Na as G; a f ggg' pH p. p. m. p. p.111 p. p. m. pfpumv 1 Free Mineral Acidity.

The remaining cartridges are exhausted in a similar manner,one at a time, at regular intervals.

After 34. weeks, the final cartridge, upon .being exhausted by water containing120 p. p, m. ofsodium, 125 p. p m. of calcium, 126 p. p. In. of.

chloride and 129 p. p. m. asbicarbonate, all .figures based on calcium carbonate, is found. from the following data to have a capacity of 13.6 kilograins as calcium carbonateper cubic-footof cation resin.

Properties of Efiiuent Specific lldtersh regbs taice H d mug at FMA as Na as 00 ohms I 3 ness as pH i p. p. m. p. p. m p. p. m.

Exampl Example 1 is repeated using a; resin :prepared according to U. S. Patent No. 2,228,159. as-;the1

cation active res in.-,

Upon exhaustion by water, containing; 125; p..,p.- m. as calcium carbonate of ,-sodium,, 130 p.,.p.m. ascalcium carbonate ,of calcium and chloride and 136 p. p. 1n. as calcium carbonate of;

bicarbonate, the initial capacity of the mixture is found from the following data to be 15.7 kilograins as calcium carbonate per cubic foot of cation resin:

Properties of Efliuent Specific P i. 30 00.. H d t mug at FMA as Na as 00 a m ohms 2 ness as pH p. p. m. p. p.111. p. p. m. p

After 40 Weeks, the final cartridge is exhausted with water cQntaining as calcium carbonate, 131 p, .p. ,m. of sodium, 118 p. p. m. of calcium and chloride and 128p. p. m. of bicarbonate and from the following data its capacity is found to be 13.6;ki1ograins of calcium carbonate per cubic foot of cation resin:

Properties of Efliuent Q eciflcresist- Liters I ance at C. through in ohms, FMA 2 Hardness pH asp. p. in. p. m; as p. p. m.

Example 3 A .series,v of, cylindrical containers about 16 inches long and about 3 inches in diameter. .Which. aremade of cardboardlined with metal foil and coated.within vasphaltum or other water. proofing. material are provided ,with a liquid. inlet at the,

bottom of the container and a liquid, outlet at thetop of the container. These mayconsistsimply of atcork through which extends a glass .tube. onto whichis attached rubber tubing.

Thecontainers orcartridges are all packed in an identical manner with alternate layers .of an.

activated and rinsed granular cation active resin manufactured accordingto U. S. Patent,No-

2,228,159 and an activated and rinsed anion resin A? prepared as,described.in,detail below, saidv layers, being packed suificiently tightlyto, prevent substantial intermixing of the twotypes. of resin at, the interfaces.

In .ordergto determine the initialcapacity of.

the particular combination, a single cartridge is Properties of Eflluent Specific c1 Hersh $0 1 1; H 1

mug at FMA as Na as 00 as at ohms 7 ncss as pH,-',

1 P. m. p p. m. p.- p. m. pflphmh The remaining cartridges are exhausted ina of containing additional -CH2CH2NH-'- groups similar manner, one at a time, at regular interg vals. After 40 weeks, the final cartridge, upon" being exhausted by water containing, as calcium carbonate, 126 p. p. m. of-sodium,' 133 p. 1). mi

as calcium, 131 p. p. m. as chloride and 134 p. p. m.

as bicarbonate, is found from the following data to have a capacity of 12.5 kilograins as calcium carbonate per cubic foot of cation resin Properties of Eflluent Specific tgiltersh regis ttglce d roug at in FMA a C0 Har ohms s a as 2 as ness as pH p. p. m. p. p. m. p. p. m. PCP. l

The present invention is not limited to the combination of the particular anion and cation resins only in the 1:1 proportion by volume of the example.

In general, I prefer mixing the-":

resins in a proportion of 1:1 by volume but I" have found that this proportion can be varied. from 3:1, cation anion, to 1:3, cation anion-all proportions being expressed in .parts by volume.

Preparation of resin .4.

203 parts of tetraethylenepentamine (1.1 mols) 297 parts of epichlorohydrin (3.2 mols) 500 parts of water The tetraethylenepentamineis charged into a' suitable reaction vessel provided with an agitator and ameans for cooling the vessel. The water is added to the tetraethylenepentamine, there-W sulting solution is cooled to about 4447" C., and

the epichlorohydrin is added slowly while the reacting mixture is being continuously agitated and kept at a temperature between 4447 C,

After all the epichlorohydrin has been addedfth'e resulting syrup is maintained at a temperature of about C. for about 8 hours.

The gelled syrup is then heated or cured at a temperature of about 95-150 C. for 17-18 I hours. The cured resin is ground and the ground material set aside for use in the resinous mix? tures of the present invention.

The present invention is not limited to the particular resins described in the example. Any

' granular water-insoluble resinous reaction prod?- uct of an alpha-chloro-beta, gamma-epoxy corn;

pound and an alkylene polyamine in the molar.

ratio of at least 2:1 may be used in place of resin A of the example. Further details of this general type of anion active resin may be foundinthe copending application of James R. Dudley;

and Lennart A. Lundberg, Serial No. 616,644, filed September 15, 1945, now Patent No. 2,469,383; issued May 10, 1949.

According to the Dudley and Lundberg ap;

plication identified above, mixtures of two, three four, five, seven or any other number of polyin the chain between the primary aminogroups etc. Complex mixtures of polyethylene polyamines .of' high molecular weight obtained by the addition of large numbers 'of' molecules of ammonia to ethylene dibromide or ethylene dichloride and the like may be used.

' Instead of epichlorohydrin other substances having an alpha-chloro-beta, gamma-epoxy arrangement are suitable for reaction with polyamines to produce anion active resins. Among these some examples are: l

CH: CI-CHz-CH-CH c1-cm -on,

02H! o1 -cnzon cn 2)a Ha c1-oH,-oH- H CH(CHa): H

chore-011- It is essential that the molar ratio of epichlorohydrin to the polyamine be at least about 2:1 when the two substances are brought together in order to obtain insoluble resins. There is no maximum amount of epichlorohydrin which may be used but generally it should not exceed a molar ratio of 5:1 or with. polyamines having more than five-amino groups the ratio should not be greater than 1 molof epichlorohydrin for each amino group in thepolyamme. I

Any phenol-bisulfite-aldehyde condensation product, for examplethat manufactured by the Chemical Process Company under the trade name Duolite C-3 or according to U. S.,Patent No. 2,228,159, may be used in the mixtureofthe present invention.

The cation active resin may be activated by treatment with dilute acid solutions, e. g., 01-10% of hydrochloric acid, sulfuric acid, etc., followed by washing of the material with water to remove free acid.

The anion active material may be activated by treatment with a dilute solution of an alkaline material, e. g., 01-25% solution of sodium hydroxide, sodium carbonate, by corresponding potassium salts, etc.

The resin combination of the present invention may be used in a large household or industrial liquid purification installation or it may be used in a disposable cartridge. In either case the resin combination may take the form of a homogeneous mixture of the two. types of resin activekresini and cationtztactive resinin which at number, of liters of: resin. 1 Division .of .theflgure so obtained by 1,000.gives the capacityofthe resin combination 'inkilograins as calcium carbonate per cubicfoot of cation resin. This method maybe summarized by the followingworking equation Capacity (kilograms as 'CaCO /ft.)=

(gallons of good water X'gr'ains as C'aCO 'of'infiue'ntX leastsome 'ofthe anionactive resin particles are in direct contactwith-at least some of the cation active resin particles. Whenever referred to in the present specification as resin combination, this meaning is intended.

In the present specification and claims appended thereto, the term shelf life is intended to indicate the stability. upon. standing (for example, on the shelfof a supplier) of a combination of resins. If," after at least 24 weeks the resin combination has a capacity for the removal of ionizable solids from liquid media of at least 7 kilograins as calcium carbonate per cubic foot of. cation resin, then the resin combination is said tohave a satisfactory shelf life or a. shelf life of at least 24 weeks.

The term ionizable solids or ionizable materials is intended to include both volatile and non-volatile materials. The major proportion of these solids are inorganic, but some organic substances may be included. These ionizable solids are impurities in the sense that they'are not desired in admixture in the fluid to be purified but they may in themselves be valuable or desirable materials.

The capacity of the resin combination is calculated in thefollowing manner from the experimental data given in the examples. It has been found that water having a resistance of 50,000 ohms or higher is generally comparable to distilled water and of satisfactory purity. Accordingly, the measurement of the specific resistance of efiiuent over a period of time will indicate the point at which the water is no longer of the desired degree of purity, i. e., thepoint at which the resistance drops below 50,000 ohms.

- #Knowing how much water has flowed through the resin combination, it is possible to calculate the i number of gallons of good water which were pre- "pared before exhausting the resins. The number of grains of ionizable solids as calcium carbonate per gallon of infiuent is known and, by multiplying'the total number of gallons of good water by the number of grains of ionizable solids per gallon of influent, it is possible to determine "the-number of grains of ionizable solids removed "iby the resin combination from the-water which passed through. This figure is converted to grains per'cubic foot of cation resin by multiplying it by 28.3 which is equal to the number ofliters ina cubic foot, and dividing by the liters inEft. liters of resin This is.a' continuation-in-part of my copending application Serial 'No. 688,713 filed August 6, 1946, now-abandoned.

Iclaim:

1. A combination of an anion active, granular water-insoluble, resinous reaction product of x'epichlorohydrin and an alkylenepolyaminein "the ratio of at least two mols of epichlorohydrin .per mol of polyamine and a cation active "granular, water-insoluble, resin which water-insoluble, resinous reaction product of epichlorohydrinvv and tetraethylenepentamine in the ratio of 3 mols of epichlorohydrin per mol of tetraethylenepentamine and a cation active granular, water-insoluble, phenol-bisulfite-aldehyde resinous reaction product, said combination after standing for 34weeks' having a capacity for the removal of ionizable solids from aqueous solution of about 8 kilograins as'calcium carbonate per cubic foot of cation resin.

GRACE ROSE STROH.

' REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 576,452 Hart Feb. 2, 1897 2,228,159 Wassenegger et al. Jan. 7, 1941 2,404,367 Durant et al July 23, 1946 2,451,272 Blann Oct. 12, 1948 2,461,505 Daniel Feb. 15, 1949 2,469,683 Dudley et al. May 10, 1949 2,474,322 Quinn June 28, 1949 OTHER REFERENCES Ser. No. 359,575, Smit.-(A. P. C.), published May 11, 1943. 

